Orientador: Cláudio Alexandre Gobatto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Educação Física / Made available in DSpace on 2018-08-22T20:03:08Z (GMT). No. of bitstreams: 1 Sousa_FilipeAntoniodeBarros_M.pdf: 1389172 bytes, checksum: 64a13cfd94274d07ed877bcc5fc5c5f4 (MD5) Previous issue date: 2013 / Resumo: Buscando fornecer ferramentas confiáveis para avaliação do desempenho durante a corrida, o objetivo do presente estudo é comparar resultados de potência mecânica horizontal obtida através de uma proposta de fácil aplicação prática (protocolo de RAST) com aqueles oriundos de um sistema de elevada sensibilidade na avaliação de corredores. Dez estudantes universitários ativos e saudáveis do gênero masculino (19,8 ± 2,1 anos; 72,3 ± 6,8 kg; 179 ± 19 cm; 9,8 ± 5,1 %g) e nove atletas especializados em corrida de velocidade também do gênero masculino (20,1 ± 1,9 anos; 68,46 ± 6,18 kg; 178 ± 5 cm; 4,44 ± 1,18 %g) se voluntariaram para o estudo. A coleta de dados se dividiu em duas etapas: a primeira foi realizada com o grupo de indivíduos ativos, com a finalidade de acessar e comparar a reprodutibilidade do sistema de corrida atada em laboratório (CA) e o sistema de corrida semi-atada em campo (CSA). Para isso, os indivíduos realizaram uma sessão em cada ergômetro, composta por duas corridas de 35 metros divididas por um intervalo de 30 minutos e uma corrida de 35 metros em situação de corrida livre em campo. Os resultados oriundos do sistema de CSA se mostraram diferentes em magnitude, porém correlacionados com os dados de CA quando relativizados pelo peso corporal. A reprodutibilidade de ambos os sistemas foi semelhante, porém a força, velocidade e potência obtidas pelo sistema de CSA foram mais bem correlacionadas com a medida de desempenho adotada. A utilização da CSA na segunda etapa das coletas possibilitou a exclusão da influência das diferenças entre avaliações laboratoriais e de campo na análise comparativa entre o sistema e os dados oriundos das equações propostas pelo protocolo de RAST. Essa etapa consistiu da aplicação do protocolo de RAST em pista na condição de corrida livre e na condição semi-atada na amostra de atletas velocistas. Na análise das variáveis mecânicas da condição de CSA, a equação proposta pelo RAST forneceu dados com magnitude semelhante àqueles encontrados pelos sensores do protótipo. Apesar disso, é observada para força e potência uma perda na consistência intra-indivíduo entre a equação do RAST e o sistema de CSA, representado por baixos r de Pearson, e uma razoável precisão como demonstrado por coeficientes de variação por volta de 7-9%. A velocidade é a única variável que mantêm acurácia, precisão e consistência entre as ferramentas de medida. Sendo assim, é possível que as múltiplas derivações e a baixa freqüência de aquisição de dados tenham comprometido o cálculo da força e potência em atletas de elevado desempenho, não sendo sensível para o seu ranqueamento. Concluímos que o sistema de CSA fornece informações reprodutíveis e mais bem relacionadas ao desempenho de pista do que a avaliação laboratorial de CA. As equações oriundas do RAST apresentam alguma acurácia no que diz respeito à magnitude da manifestação de força e potência, porém falha em manter a consistência e precisão ao avaliar corredores de rendimento elevado, se mostrando uma ferramenta não adequada para a classificação dessas qualidades em atletas desse nível / Abstract: Seeking for reliable tools in performance evaluation during sprint running, this study aim relies on the comparison between mechanical power measurements obtained by a practical and easy application protocol (RAST protocol) with a system which provides a high data acquisition frequency. Ten healthy male college students who reported to be active in different sports disciplines (19.8 ± 2.1 years; 72.3 ± 6.8 kg; 179 ± 19 cm; 9.8 ± 5.1 %g) and nine male sprint runners (20.1 ± 1.9 years; 68.46 ± 6.18 kg; 178 ± 5 cm; 4.44 ± 1.18 %g) volunteered to take part in this investigation. The study was divided in two main parts: firstly, in order to assess and compare the laboratory tethered running (TR) system and the field semitethered running (STR) system reliabilities, the active participants undergone two sessions, each session consisting of two 35 meters sprint with a 30 minutes interval in one of the ergometers, as well as one 35 meters sprint in free running condition. STR mechanical parameters presented statistical difference towards TR, but high significance when relative to the individual body mass. The reliability of both parameters were similar, however force, velocity and power measurements were better correlated to performance in STR condition. So, using STR for the second stage of the study enables the isolation of the effect caused by differences between laboratory and field environments during the comparison among mechanical variables measured for the system and RAST's equations. During this stage, the sprint athletes underwent two RAST protocols in free running and STR condition, on two different sessions. In the STR condition, both the sensors and RAST's equations were similar concerning magnitude, but force and power calculated by the equations showed a poor consistency illustrated by weak Pearson's r, and a reasonable precision, based on CV's ranging 7-9%. Velocity parameters derivates based only in time to complete the effort maintained its accuracy, precision and consistency, so that approach is encouraged when a simple analysis in repeated sprint protocols is needed. It is possible that the low data acquisition frequency together with multiple derivations on RAST equations compromised force and power consistency in well trained sprint athletes. In conclusion, STR field evaluation provides reliable data that is more related to performance measures than the laboratory TR. Despite the maintenance of accuracy between RAST equations and STR system regarding force and power, it presented a weak precision and very low consistency when evaluating well trained sprint athletes, raising doubts about its application to evaluate this qualities in that kind of population / Mestrado / Biodinamica do Movimento e Esporte / Mestre em Educação Física

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Les études conduites au cours de ce travail de thèse ont montré que l’optimisation de la position du cycliste sur son vélo était un élément déterminant de la performance. Nos recherches ont porté sur quatre axes principaux : la conception et la validation d’outils de mesure, l’étude de la position aérodynamique, l’étude de la position assise et enfin l’étude de la position danseuse.L’ensemble des résultats obtenus montrent que la capacité de performance du cycliste peut être améliorée en position aérodynamique en augmentant le ratio entre la puissance mécanique (Pméca) et la surface frontale effective (SCx). Le confort représente également un des principaux facteurs de la performance en contre‑la‑montre (CLM) puisqu’il détermine l’aptitude du cycliste à maintenir sa position au cours du temps. Nos travaux montrent une amélioration du confort avec des semelles orthopédiques, chez les cyclistes affectés par une inégalité de longueur des membres inférieurs (ILMI), liée à une réduction des mouvements du bassin. Une correction orthopédique induit également une augmentation du rendement énergétique (+5,7 %). Ainsi, les cyclistes affectés par une ILMI sont recommandés de la compenser avec des semelles orthopédiques individualisées de façon à améliorer leur performance en CLM. Lors d’une étude préliminaire, nous avons également montré la relation entre les mouvements de la tête et le SCx, c’est pourquoi les cyclistes doivent réduire au maximum ces mouvements afin de minimiser leur SCx et ainsi maximiser leur performance. L’évaluation de la position aérodynamique doit être réalisée en conditions réelles de locomotion, que ce soit pour l’évaluation de S ou de SCx. Le développement de nos deux applications est donc un réel atout pour l’évaluation de la traînée aérodynamique (Ra) de manière individualisée dans les prochaines années puisqu’elles rendent le traitement plus accessible aux entraîneurs. Enfin, bien que nous ayons initié une nouvelle méthodologie d’évaluation de la position aérodynamique en associant numérisation 3D et modélisation numérique de la mécanique des fluides, cette méthode serait plutôt recommandée pour l’individualisation de l’équipement.La position assise peut également être optimisée en augmentant l’indice d’efficacité mécanique (IEM) du cycliste, quel que soit le niveau et le sexe. Cette augmentation de l’IEM passe principalement par une diminution de la force résistante (Fres) dans la phase de montée de la pédale. Malgré tout, le cycliste ne doit pas tirer sur la pédale pour générer un couple propulsif car cette stratégie est contre-productive d’un point de vue énergétique. Il serait intéressant d’étendre notre première étude, établie en laboratoire, sur le terrain pour analyser les adaptations biomécaniques du pédalage des cyclistes aux conditions rencontrées sur le terrain. Les différences observées en laboratoire, sur terrain plat et en montée laissent penser que les cyclistes adaptent leur pédalage selon les conditions dans lesquelles ils évoluent.Enfin, les travaux menés sur la position danseuse montrent que les cyclistes augmentent leur coût mécanique (CM) (+4,3 % en laboratoire vs. +19 % sur le terrain) par rapport à la position assise alors que la consommation d’oxygène reste stable entre les deux positions. Ces pertes mécaniques en position danseuse sont principalement dues à l’augmentation du coefficient de roulement (Cr) due aux oscillations latérales du vélo et donc à la torsion des pneus. Puisque les pertes mécaniques sont plus élevées sur le terrain que sur tapis roulant, d’autres facteurs semblent contribuer à cette différence comme la Ra (~10 W), le matériel utilisé par les cyclistes, le Cr de la route et la technique adoptée. Aussi, la position danseuse induit une augmentation du CM pour maintenir la vitesse de déplacement face aux variations de pente en montée. Les cyclistes sont donc fortement recommandés de réduire l’augmentation du CM en position danseuse comparée à la position assise. / The studies conducted during this PhD research showed that optimizing the position of the cyclist on the bicycle is a key factor influencing cycling performance. Our research focused on four main axes: the design and validation of measurement tools, the study of the aerodynamic position, the study of the seated position and the study of the standing position.All the results showed that the performance capacity of cyclists can be improved in aerodynamic position by increasing the ratio between the mechanical power (PO) and the drag area (ACd). Comfort is also a significant factor in time trial (TT) performance as it determines the ability of the cyclist to maintain position over time. Our works show that comfort can be improved via orthopaedic correction in cyclists affected by lower limb length inequality (LLLI) in the TT position, related to a reduction in pelvis movements. The orthopaedic correction also induces an increase in gross efficiency (+5.7%). Thus, this improvement in comfort could increase the PO and/or the amount of time the aerodynamic position can be maintained during a TT. Therefore, cyclists affected by LLLI should compensate LLLI with individualised foot orthotics to improve their TT performance. In a preliminary study, we also showed that there is a relationship between head movements and ACd. Therefore, cyclists should minimise these movements to minimise their ACd and maximise their performance. Aerodynamic position must be evaluated in real cycling locomotion, whether for the evaluation of A or ACd. We have developed two applications that are a real asset for the dynamic evaluation of aerodynamic drag (Ra) as they make the data analysis more accessible to coaches. Finally, although we have initiated a new method to assess ACd in the aerodynamic position by combining 3D scanning and computational fluid dynamics simulation, this method is also recommended for individualisation of cycling equipment.The seated cycling position can also be optimised by increasing the cyclists’ force effectiveness (FE), regardless of practice level or gender. This increase in FE is mainly due to a decrease in resistive force (Fres) during the upstroke phase of pedalling. Nevertheless, the cyclist should not pull on the pedal to generate propulsive torque because this strategy is counterproductive from an energy point of view. It would be interesting to extend our first study, which was set up in a laboratory, to the field to analyse the biomechanical adaptations of cyclists to the real conditions of locomotion. The differences observed in the laboratory, on level ground and over an uphill grade suggest that cyclists adjust their pedalling technique according to the conditions under which they are performing.Finally, studies of the standing cycling position show that cyclists increase their mechanical cost (MC) (+4.3% in the laboratory vs. +19% in the field) compared to the seated position; however, oxygen consumption was similar between the two positions. These mechanical losses (13 W in the laboratory vs. 49 W in the field) in the standing position are mainly due to increased rolling resistance coefficient (Crr), induced by the lateral sways of the bicycle and therefore torsion of the tyres. Because the observed mechanical losses are higher in the field than on the treadmill, other factors could contribute to this difference, such as Ra (~10 W), the equipment used by cyclists, the Crr of the road surface and the technique adopted. Also, the standing position induces an increase in MC to maintain constant speed when faced with uphill slope variations. Cyclists are therefore strongly recommended to reduce the increase of the MC in standing position compared to the seated position. This reduction in mechanical losses can be achieved by decreasing lateral sways and Ra.